This invention concerns a device for twisting rope-shaped material, particularly of large cross section, with changing twist direction (SZ), consisting of a rotor that changes direction and/or RPM, with two opposing chain drives that are parallel to the rotor axis along an endless path, for collet chucks that grip the material and guide it along a prescribed path determined by a pressure rail, and which subsequently release the material.
Devices of this type have been known for a long time as shown, for example, in U.S. Pat. No. 4,311,002. See also "New developments in SZ-stranding" by Dipl.-Ing. Dieter Vogelsberg in Wire and Cable Panorama, Aug./Sept. 1985, DKS Fachverlag GmbH, Dusseldorf. Such devices provide the possibility of twisting large cross section leads, such as are required to transmit and distribute electric power, into a cable core according to the SZ-twisting process, used until the priority date of U.S. Pat. No. 4,311,002 only for communication cable leads. At the end of the above-cited article is described a manufacturing program, for example, SZ-stranding machines for optical fiber conductors (small cross-section) or SZ-stranding machines for sheathed power cable on IKV cable (larger cross-section). The individual leads are gathered into a bundle, then held by collets of the device, and, while held along a determined path, they are twisted by rotation of the rotor, by changing the twist direction and/or the RPM. The release of the twisted leads at the end of the defined path (storage path) is caused by return springs located in each collet chuck half. Since the reliability of the collet release, and therefore the reliability of releasing the twisted material, depends on the reliability of the springs, there is occasionally the danger of a collet chuck seizure disturbing the synchronized operation along the prescribed chain path. This danger exists especially during high production speeds, due to the corresponding centrifugal forces taking place at that time.